Fastener Stringer Provided with Knit Tape

ABSTRACT

The present invention provides a fastener stringer comprising a knit fastener tape of a warp knit structure having an element mounting portion and a tape main portion, and a coiled plastic element row sewed on the element mounting portion wherein, two needle yarns for sewing the element row on the element-mounting portion are so arranged that they interpose a wale whereby two sewing lines, are formed, and any one of knitting yarns that straddle an inside sewing line of the two sewing lines has a fineness of 72-330 dTex and substantially all of the other knitting yarns have a fineness of 56-167 dTex, provided that the one of the knitting yarns that straddle the inside sewing line of the two sewing lines is thicker than substantially all of the other knitting yarns. The fastener stringer has both a light weight and a high strength.

FIELD OF THE INVENTION

The present invention relates to a fastener stringer provided with a knit tape. Further, the present invention relates to a slide fastener chain and a slide fastener using the fastener stringer.

BACKGROUND OF THE INVENTION

Slide fasteners are opening-closing tools widely used not only in articles of daily use such as garments, bags, shoes and sundry goods, but also in articles of industry such as water storage tanks, fishing nets and space suits.

In general, a slide fastener is comprised of three main parts, namely, a pair of long tapes, a number of elements sewed on along with a side edge of each tape and functioning as engaging parts of the fastener, and a slider for controlling the opening and closing of the fastener by engaging and disengaging the elements.

The tape for the slide fastener (hereinafter called “fastener tape”) comprises a tape main portion which is to be sewed on the body of an article and an element-mounting portion on which the elements are mounted. The elements are mounted on the element-mounting portion with sewing yarns. Selvage yarn may be provided to the end of the tape main portion to prevent the tape main portion from fray. The tape on which the elements have been mounted is called “a fastener stringer”.

Heretofore, woven tapes have been used as materials for fastener tapes, but recently knit tapes formed with a warp-knit structure have become widely used for the reason of its superior softness and shape stability as compared to the woven tapes.

Various techniques have been proposed for improvement of the properties of the knit tapes. Among them, there is a technique in which an improvement is made by partly thickening yarns that constitute a warp-knit structure.

For example, Japanese Utility Model Examined Publication No. S59-29525 (Patent document 1) proposed an improvement of a slide fastener comprised of a tape and continual zigzag elements which clamp opposite surfaces of the tape and are fixed to the tape with a sewing yarn, wherein there is no fear the elements might slip out of the tape and a stable meshing is attained.

According to Patent document 1, the wales on which the elements are mounted are formed in a higher position with a broader width than the other wales, whereby the elements can be mounted more strongly. As an example, the document discloses that, at the side edge on which the continual clamping-type elements are mounted, the tricot knitting yarn stretched between the first and second needle arrays and the chain knitting yarn provided on the second and third needle arrays are both thicker than the other yarns.

Japanese Patent Examined Publication No. S52-18616 (Patent document 2) is related to a textile band for producing slide fasteners. It discloses that in order to strengthen a band edge portion when uniting a pair of support bands to form a single broader textile band, the chain knitting yarn defining the band edge portion, the two-needle fringe stitch yarn and the inlaid yarn are thicker than the other yarns. It discloses that this will improve the strength and the resilience of the support bands.

Japanese Patent Un-examined Publication No. H9-318 (Patent document 3) proposes a narrow warp-knit tape for a slide fastener having a plurality of parallel longitudinal wales, characterized in that a fastener element-mounting portion has a longitudinally non-stretchable knit structure (Example section describes a knit structure of interlooping chain knitting yarns with other knitting yarns), the knitting yarn for the outer wale of said knit structure being thick while the tape main portion has a longitudinally stretchable structure (Example describes a knit structure of interlooping textured yarns of single cord knitting with other knitting yarns made of multifilament yarn), the outer edge of said knit structure being formed by interlooping two kinds of thick knitting yarns. According to this proposal, since the fastener element-mounting portion has a longitudinally non-stretchable knit structure and its edge is reinforced, the fastener elements can be mounted in a stable condition and the meshing operation can be carried out accurately and smoothly.

PRIOR ART DOCUMENTS Patent Documents

-   1: Japanese Utility Model Examined Publication No. S59-29525 -   2: Japanese Patent Examined Publication No. S52-18616 -   3: Japanese Patent Un-examined Publication No. H9-318

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

These prior arts do not intend to achieve weight reduction of slide fasteners, or to provide any suggestion to the solution. It will be advantageous if a light weight slide fastener is provided while retaining the strength in goods such as portable wind breakers used in running, cycling, trekking or other outdoor sports, laces for women, cardigans for infants, or other goods which place great importance on lightness.

On the other hand, the elements to be mounted on the fastener tape include a single piece element as represented by a metal element and a plastic element molded on a tape by injection, and a continuous element represented by a coiled plastic element. Among them, the coiled plastic element is light in weight and highly flexible. Since it is desirable for the above-mentioned portable goods to be folded and easily housed in a pocket or the like, it will be advantageous to pursue the improvement of the fastener tapes, taking the type of element into consideration when realizing the lightness of slide fasteners.

Therefore, an object of the present invention is to provide a slide fastener stringer of light weight and high strength, using a knit tape having a warp-knit structure and a coiled plastic element. Another object of the invention is to provide a slide fastener chain provided with such fastener stringer. Yet another object of the present invention is to provide a slide fastener provided with such slide fastener chain.

Means for Solving the Problem

The present inventors considered to make the knitting yarns thinner but found that, when the overall yarns were made thinner, the necessary strength (particularly, crosswise tensile strength) could not be obtained. However, after extensive studies, the inventors have found that when two needle yarns for sewing on the elements are so arranged that they interpose a single wale, whereby two sewing lines are formed, and when any one of knitting yarns that straddle an inside sewing line of the two sewing lines is made sufficiently thick, a practical strength can be obtained even if the other yarns are thin.

Based on the above-mentioned findings, the present invention provides, in one aspect, a fastener stringer (102) comprising a knit fastener tape (100, 200) of a warp-knit structure having an element-mounting portion (A) and a tape main portion (B), and a coiled plastic element row (101) sewed on the element-mounting portion (A), wherein:

two needle yarns (106) for sewing the element row (101) on the element-mounting portion (A) are so arranged that they interpose a single wale (W2), whereby two sewing lines are formed, and

any one (104′, 105″ or 112′) of knitting yarns that straddle an inside sewing line of the two sewing lines has a fineness of 72-330 dTex, and substantially all of the other knitting yarns have a fineness 56-167 dTex,

provided that the one (104′,105″ or 112′) of knitting yarns that straddle the inside sewing line of the two sewing lines is thicker than substantially all of the other knitting yarns.

In another aspect of the present invention, the present invention provides a fastener stringer (102) comprising a knit fastener tape (100, 200) of a warp-knit structure having an element-mounting portion (A) and a tape main portion (B), and a coiled plastic element row (101) sewed on the element-mounting portion (A), wherein:

two needle yarns (106) for sewing the element row (101) on the element-mounting portion (A) are so arranged that they interpose a single wale (W2), whereby two sewing lines are formed,

any one (104′,105″ or 112′) of knitting yarns that straddle an inside sewing line of the two sewing lines has a fineness of 72-330 dTex, and substantially all of the other knitting yarns have a fineness 56-167 dTex, and

the outermost knitting yarn (103′) in the element-mounting portion (A) has a fineness of 66-275 dTex,

provided that the one (104′,105″ or 112′) of knitting yarns that straddle the inside sewing line of the two sewing lines as well as the outermost knitting yarn (103′) in the element-mounting portion (A) are thicker than substantially all of the other knitting yarns.

In one embodiment of the fastener stringer according to the present invention, the number of stitches where three knitting yarns are interlooping in one stitch account for at least 50% of the total number of stitches.

In a further embodiment of the fastener stringer according to the present invention, the tape (100, 200) is knitted with three types of yarns in total, namely, chain knitting yarn (103,103′), tricot knitting yarn (104, 104′) and one of satin knitting yarn (105, 105′, 105″) and modified two-needle stitch yarn (112, 112′).

In a further embodiment of the fastener stringer according to the present invention, the one (104′, 105″ or 112′) of knitting yarns that straddle the inside sewing line of the two sewing lines is selected from the group consisting of tricot knitting yarn (104′), satin knitting yarn (105″) and modified two-needle stitch yarn (112′).

In a further embodiment of the fastener stringer according to the present invention, the wale (W2) which is interposed by the two needle yarns (106) for sewing on the element row (101) is the second wale as counted from the outermost side of the element-mounting portion.

In a further embodiment of the fastener stringer according to the present invention, the needle yarn (106) has a fineness of 100-350 dTex.

In a further aspect of the present invention, the present invention provides a slide fastener provided with the fastener stringer (102) according to the present invention.

In a further aspect of the fastener stringer according to the present invention, the present invention provides an article on which the slide fastener according to the present invention is sewed.

Effect of the Invention

According to the present invention, a fastener stringer of a light weight and a high strength is provided. Also, softness of the fastener stringer is increased by using thinner yarns as compared to the prior art fastener stringer.

BRIEF EXPLANATION OF THE INVENTION

FIG. 1 shows a knit structure of the fastener tape according to the first example of the present invention.

FIG. 2 shows structures of respective knitting yarns used in the first example of the present invention.

FIG. 3 is a cross sectional view of a fastener stringer formed by sewing the elements on the fastener tape.

FIG. 4 shows a modified embodiment of the satin knitting yarn (open loop) capable of being used in the first example.

FIG. 5 shows a modified embodiment of the first example wherein the thick knitting yarn which straddles the inside sewing line is a satin knitting yarn.

FIG. 6 shows a knit structure of the fastener tape according to the second example of the present invention.

FIG. 7 shows structures of respective knitting yarns used in the second example of the present invention.

FIG. 8 is a modified embodiment of the second example wherein the thick knitting yarn which straddles the inside sewing line is a modified two-needle stitch yarn.

MODES FOR CARRYING OUT THE INVENTION

The fastener stringer according to the present invention includes, as the essential components, a knit fastener tape of a warp-knit structure having a tape main portion and an element-mounting portion, and a coiled plastic element row sewed on the element-mounting portion. The coiled plastic element row is adopted because it is best suited for the purpose of the present invention in view of its light weight, flexibility and an easy-housed nature. As plastics for the material of the element row, polyester, nylon, polypropylene and acrylic may be cited but polyester is preferred because it has a good sewing property as well as a high strength, etc.

To establish a high strength capable of withstanding the practical use as a slide fastener while knitting yarns constituting the warp-knit structure are generally made thin, it is preferred that the outermost knitting yarn in the element-mounting portion be sufficiently thick. This is because, by doing so, the elongation of the fastener tape is suppressed and the width of the tape is stabilized, thereby enhancing the sewing property of the elements. A knitting yarn having a fineness of typically 66-275 dTex, preferably 78-167 dTex may be used. As the knit structure used here, chain knitting is preferred because the chain knitting strengthens the edge of the element-mounting portion and the elongation of the warp-knitted tape is also suppressed, whereby the work of mounting the fastener element becomes easier.

Further, in the present invention, two needle yarns for sewing the element row on the element-mounting portion are so arranged that they interpose a single wale, whereby two sewing lines are formed. These sewing lines, which interpose the single wale, are made up of a first sewing line arranged in the outside of the wale in the element-mounting portion, and a second sewing line arranged in the inside of the first sewing line in the element-mounting portion. The first sewing line is an outside sewing line which will be explained later, and the second sewing line is an inside sewing line which will be also explained later. By performing the mounting of the element row in such a way, it is possible to compensate for the otherwise lowering the mounting strength and stability of the elements incurred by the thinned yarns. In order to stabilize the dimension of the gap formed between the opposing edges of the fastener tapes when the elements of the right and left fastener stringers are meshed, the wale interposed by the two needle yarns for sewing on the element row is typically the second wale as counted from the outermost side of the element-mounting portion.

In light of weight reduction of the slide fastener, which is the object of the present invention, thin yarns are desirably adopted as the needle yarn. Thin yarns also contribute to the improvement of softness of the slide fastener. If, however, they are excessively thin, practical mounting strength and stability cannot be attained. Accordingly, it is preferable to use yarns having a fineness of 100-350 dTex, it is more preferable to use yarns having a fineness of 110-250 Tex. The same can be applied to the fineness of looper yarns used in combination with the needle yarn.

According to the present invention, the fineness of any one of the knitting yarns which straddle the inside sewing line of the two sewing lines thus formed is made thick. Although there may be plural sewing yarns in the tape which straddle the inside sewing line, only one of them should have a large fineness. Specifically, the knitting yarn having a fineness of 72-330 dTex, preferably 78-235 dTex, more preferably 78-167 dTex is used. By thickening the knitting yarn straddling the inside sewing line, the fastener tape is prevented from tearing apart along the sewing line when a crosswise tensile force is applied to the fastener tape. The knitting yarn to be thickened may include a tricot knitting yarn, a satin knitting yarn and a modified two-needle stitch yarn. The term “a modified two-needle stitch yarn” herein means a knitting yarn arranged in a zigzag pattern while forming a loop around two adjacent wales in each course.

Thus, by sufficiently thickening any one of the knitting yarns which straddle the inside sewing line and preferably also the outermost knitting yarn in the element-mounting portion, a slide fastener having a sufficient strength (particularly, crosswise tensile strength) can be obtained, even though the fineness of substantially all of the other knitting yarns are made smaller than these knitting yarns within the range of 56-167 dTex, typically 66-110 dTex, more typically 66-84 dTex. In a typical embodiment, the outermost knitting yarn in the element-mounting portion and the thick single knitting yarn straddling the inside sewing line have a different fineness from substantially all of the other knitting yarns by at least 10 dTex, more typically by at least 20 dTex, for example, by 10-40 dTex.

The reason why the term “substantially” is used in the preceding paragraph is as follows. In knitted fastener tapes, there is a case where the tape main portion is centered and the right and left sides have a warp-knit structure capable of functioning as the element-mounting portion in order to prevent users from mistaking the tape main portion for the element-mounting portion and consequently mounting the elements on the tape main portion. In such a case, in spite of the presence of unused element-mounting portion, it should be understood that such embodiment belongs to the scope of the present invention. In addition, even if one or two thick yarns are used in a place where the present invention does not stipulate for form's sake with an intension of avoiding the technical scope of the present invention, it should be understood that such embodiment also belongs to the present invention.

The width of the tape for the foregoing slide fastener is 11-13 mm. Slide fasteners have element rows and tapes in different sizes depending on their use. Specifically, the wire diameter, width and thickness of the coiled element row, the size of meshing heads by which element rows are mutually engaged, and the width and thickness of the tape are different. This is because as the sizes of the element row and the tape become larger, the crosswise tensile strength can be enhanced. Accordingly, when the tape size is made larger, and its width is set at 14-17 mm, it is preferred that the fineness of any one of the knitting yarns straddling the inside sewing line of the two sewing lines be set at 235-330 dTex, the fineness of the substantially all of the other knitting yarns except for the outermost knitting yarn in the element-mounting portion be preferably set at 110-167 dTex. Also, the fineness of the outermost knitting yarn in the element-mounting portion is preferably set at 167-275 dTex, and the fineness of the needle yarn and the looper yarn is preferably set at 250-350 dTex.

The element-mounting portion and the tape main portion may be made of knitting yarns of the same fineness and material. Alternatively, knitting yarns for the element-mounting portion and the tape main portion may be different from each other. Also, regardless of whether it is the element-mounting portion or the tape main portion, the fineness and the material of each knitting yarn may be changed.

As material for the knitting yarns, polyester, nylon, polypropylene, acrylic and the like which have been conventionally used in the field of the slide fasteners may be used. However, polyester is preferable in order to use the same material as the element for minimizing the color difference between them after dyeing. The knitting yarn may be formed with a monofilament or with a multifilament made by bundling a plurality of monofilaments. For example, a single yarn having a fineness of 250 dTex is formed with a multifilament bundling 50 monofilaments of 5 dTex.

As for the knitting yarn itself for knitting the fastener tape, any known knit structures may be adopted such as, but not limited to, chain knitting yarn, tricot knitting yarn, satin knitting yarn, and modified two-needle stitch yarn. However, in consideration of reduction of the load on a knitting machine while maintaining the fastener tape bulky, it is preferred the fastener tape be knitted with three types of yarns, namely, chain knitting yarn, tricot knitting yarn and one of satin knitting yarn and modified two-needle stitch yarn. Closed stitch and open stitch may be arbitrary selected depending on the necessary strength of the tape.

In a preferred embodiment of the fastener stringer according to the present invention, it is preferable that the number of stitches where three knitting yarns are interlooping in one stitch (a three-loop knit structure) account for at least 50%, more preferably at least 60% of the total number of stitches. By increasing the amount of three-loop knit structure, the advantages of increased strength, texture and bulkiness can be obtained. Too many two-loop structures will fail to obtain sufficient strength, texture and bulkiness. Too many four-loop structures will fail to sufficiently achieve weight reduction of slide fasteners, which is the original object of the present invention. Furthermore, too many three-loop knit structures will also fail to sufficiently achieve weight reduction of slide fasteners, which is the original object of the present invention, due to an increase of the number of knitting yarns for forming the loop. Accordingly, it is preferable that the number of stitches where three knitting yarns are interlooping in one stitch (a three-loop knit structure) account for less than 80% of the total number of stitches.

A slide fastener is completed by meshing a pair of fastener stringers together to form a fastener chain, and then attaching a slider and top and bottom end stops to it. The slide fastener according to the present invention can be sewed on various articles and used as an opening/closing tool. Particularly, it can be suitably used with articles such as laces, cardigans, window breakers, etc. for which lightness is required.

EXAMPLES

In the following, examples of the present invention will be explained in details. It should be understood that the present invention is not restricted to the following examples but various modifications may be possible within the scope of the present invention.

First Example

FIG. 1 shows a knit structure diagram of a fastener tape (100) according to the first example of the present invention. The knit structure was produced by using a crochet knitting machine. The material for the knitting yarns was polyester. This fastener tape (100) is configured with the 1st wale (W1) to the 12th wale (W12) which are aligned in sequence from the left. The 1st wale (W1) to the 3th wale (W3) form the element-mounting portion (A) and the 4th wale (W4) to the 12th wale (W12) form the tape main portion (B).

<Knit Structure>

The knit structure of the fastener tape (100) will now be explained. The element-mounting portion (A) and the tape main portion (B) are, as illustrated in FIG. 2, knitted with chain knitting yarns (103, 103′) of 1-0/0-1 with open loop, tricot knitting yarns (104, 104′) of 1-0/1-2 with closed loop, and satin knitting yarns (105) of 3-4/1-0 with closed loop. In FIG. 2, individual knit structures in the knit structure diagram are illustrated. Beginning from the left in the drawing, a thick chain knitting yarn (103′), a chain knitting yarn (103), a tricot knitting yarn (104), a thick tricot knitting yarn (104′) and a satin knitting yarn (modified tricot knitting yarn) (105) are shown.

Among the knitting yarns constituting the fastener tape of the first example, the tricot knitting yarn (104′) which straddles the 2nd wale (W2) and the 3rd wale (W3) as well as the chain knitting yarn (103′) disposed on the 1st wale (W1) are thick and these knitting yarns have the same fineness of 110 dTex. As for the 10th wale (10W) to the 12th wale (W12), the tricot knitting yarn which straddles the 10th wale (W10) and the 11th wale (W11) and the chain knitting yarn disposed on the wale 12 (W12) are thick and have a fineness of 110 dTex so that they can be also used as the element-mounting portion (A). The other knitting yarns are thin and have a fineness of 78 dTex. It is to be noted that the fineness of each knitting yarn is not restricted to that used in the example. For example, the tricot knitting yarn (104′) straddling the 2nd wale (W2) and the 3rd wale (W3) may have the largest fineness of 78 dTex, and the chain knitting yarn (103′) disposed on the 1st wale (W1) may have 72 dTex, and the other knitting yarns may have the smallest fineness of 66 dTex. Alternatively, the tricot knitting yarn (104′) straddling the 2nd wale (W2) and the 3rd wale (W3) may have the largest fineness of 72 dTex, and the chain knitting yarn (103′) disposed on the 1st wale (W1) and the other knitting yarns may both have the same 66 dTex.

As shown in FIG. 1, in the first example, the number of stitches where three knitting yarns are interlooping in one stitch (forming a three-loop knit structure) to the total number of stitches three-loop knit structure is 2/3.

In the first example, the satin knitting yarns (105) form a knit structure such that they straddle four wales. In the fastener tape illustrated in FIG. 1, the total number of stitches is 72. Among them, the number of stitches where three knitting yarns are interlooping in one stitch (forming a three-loop knit structure) is 48. Accordingly, the number of stitches where three knitting yarns are interlooping in one stitch to the total number of stitches reaches about 68%. The knit structure formed by the satin knitting yarns is not restricted to that used in the example. For example, satin knitting yarns may form a knit structure such that they straddle adjacent three wales. By doing so, the number of stitches where three knitting yarns are interlooping in one stitch reaches 54. Accordingly, the number of stitches where three knitting yarns are interlooping in one stitch to the total number of stitches reaches about 75%. Further, satin knitting yarns may form a knit structure such that they straddle adjacent five wales and thus the number of stitches where three knitting yarns are interlooping in one stitch reaches 42. Accordingly, the number of stitches where three knitting yarns are interlooping in one stitch to the total number of stitches reaches about 58%.

In the first example, the satin knitting yarn (105) is knitted with closed loop, but as show in FIG. 4, the satin knitting yarn (105′) of 4-3/0-1 may be knitted with open loop. Also, with respect to the chain knitting yarn (103, 103′) and the tricot knitting yarn (104,104′), selection of closed loop or open loop may be arbitrary made.

In the first example, the tricot knitting yarn straddling the 2nd wale (W2) and the 3rd wale (W3) adopts a thick yarn, but as shown in FIG. 5, the satin knitting yarn (105″) having stitches alternately on the 1st wale (W1) and the 4th wale (W4) may be made thick. Furthermore, though not illustrated, the satin knitting yarn having stitches alternately on the 2nd wale (W2) and the 5th wale (W5) may be made thick. This is because all these yarns straddle the 2nd wale (W2) and the 3rd wale (W3).

<Mounting of the Elements>

FIG. 3 shows a cross sectional view illustrating the configuration in which the element row (101) has been mounted on the fastener tape (100) to form a fastener stringer (102). Two needle yarns (106) are arranged to sew on the element row (101). By this arrangement, the outside sewing line is formed between the 1st wale (W1) and the 2nd wale (W2), and the inside sewing line is formed between the 2nd wale (W2) and the 3rd wale (W3). In this case, a coiled polyester element row is used.

The procedure for mounting the element row (101) will now be explained. First, a core cord (108) is inserted through the hollow portion of the element row (101), and the element row (101) is placed in a given position on the element-mounting portion (A) with the meshing head (109) of the element row (101) orienting outwardly. Next, a sewing needle is stuck through a groove (G1) between the 1st wale (W1) and the 2nd wale (W2) and a groove (G2) between the 2nd wale (W2) and the 3rd wale (W3), whereby two needle yarns (106) and a single looper yarn (107) functioning as sewing yarns tighten together the upper leg (110) and the lower leg (111) of the element row (101), so that the element row (101) and the core cord (108) are sewn on the fastener tape (100). The fineness of the needle yarn (106) and the looper yarn (107) was set at 139 dTex.

<Area Density>

The fastener stringer according to the first example has an area density of 150-175 g/m², which is only 60% by weight of the conventional knit fastener tape.

<Strength Test>

Two fastener stringers were prepared according to the first example, and they were meshed together to form a fastener chain, and the crosswise tensile strength was determined according to the JIS-S3015. The result of 557N was obtained.

On the other hand, as a comparative example, a fastener chain (comparative example 1) using a knit fastener tape in which the outermost knitting yarn in the element-mounting portion has a fineness of 110 dTex and substantially all of the other knitting yarns have a fineness of 84 dTex was prepared and the crosswise tensile strength was determined. The result of 444N was obtained.

From this result, it is ascertained that, by increasing the fineness of only one of the knitting yarns which straddle the inside sewing line of the two sewing lines, the fastener tape is not torn apart along the sewing line when a crosswise tensile force is applied to the fastener chain, and the strength has been remarkably enhanced as compared to the fastener chain in which substantially all the knitting yarns are thin, and a strength comparative to the conventional fastener chain using only thick knitting yarns can be achieved.

Second Example

FIG. 6 illustrates a partial knit structure of a fastener tape (200) according to the second example of the present invention. The knit structure was produced by using a crochet knitting machine. This fastener tape (200) is a modification of the knit structure of the first example in that the satin knitting yarn was changed to a modified two-needle stitch yarn of 3-4/1-0. Accordingly, the fastener tape (200) of this second example is knitted with three types of knitting yarns, namely, chain knitting yarns (103, 103′), tricot knitting yarns (104, 104′) and modified two-needle stitch yarns (112). In FIG. 7, individual knit structures in the knit structure diagram are illustrated. Beginning from the left in the drawing, a thick chain knitting yarn (103′), a chain knitting yarn (103), a tricot knitting yarn (104), a thick tricot knitting yarn (104′) and a modified two-needle stitch yarn (112) are shown.

In the second example, the number of stitches where three knitting yarns are interlooping in one stitch (forming a three-loop knit structure) to the total number of stitches is 7/12.

In the second example, the chain knitting yarns (103, 103′) are knitted with open loop, the tricot knitting yarns (104, 104′) are knitted with closed loop, but selection of closed loop or open loop may be arbitrary made.

In the second example, the tricot knitting yarn (104′) which straddles the 2nd wale (W2) and the 3rd wale (W3) adopts a thick yarn. However, as shown in FIG. 8, the modified two-needle stitch yarn (112′) which straddles from the 1st wale (W1) to the 4th wale (W4) may be made thick. Also, though not illustrated, the modified two-needle stitch yarn which straddles from the 2nd wale (W2) to the 5th wale (W5) may be made thick. This is because all these yarns straddle the 2nd wale (W2) and the 3rd wale (W3).

When the knitted fastener tape according to the second example was used, a fastener chain having both a light weight and a high strength was obtained like the first example.

EXPLANATION OF THE SYMBOLS

-   100 fastener tape -   101 element row -   102 fastener stringer -   103, 103′ chain knitting yarn -   104, 104′ tricot knitting yarn -   105, 105′, 105″ satin knitting yarn -   106 needle yarn -   107 looper yarn -   108 core cord -   109 meshing head -   110 upper leg -   111 lower leg -   112, 112′ modified two-needle stitch yarn -   200 fastener tape -   A element-mounting portion -   B tape main portion -   G1,G2 groove -   W1-W12 1st wale-12th wale 

1. A fastener stringer comprising a knit fastener tape of a warp-knit structure having an element-mounting portion and a tape main portion, and a coiled plastic element row sewed on the element-mounting portion wherein: two needle yarns for sewing the element row on the element-mounting portion are so arranged that they interpose a single wale, whereby two sewing lines are formed, and any one of knitting yarns that straddle an inside sewing line of the two sewing lines has a fineness of 72-330 dTex, and substantially all of the other knitting yarns have a fineness 56-167 dTex, provided that the one of knitting yarns that straddle the inside sewing line of the two sewing lines is thicker than substantially all of the other knitting yarns.
 2. A fastener stringer comprising a knit fastener tape of a warp-knit structure having an element-mounting portion and a tape main portion, and a coiled plastic element row sewed on the element-mounting portion, wherein: two needle yarns for sewing the element row on the element-mounting portion are so arranged that they interpose a single wale, whereby two sewing lines are formed, any one of knitting yarns that straddle an inside sewing line of the two sewing lines has a fineness of 72-330 dTex, and substantially all of the other knitting yarns have a fineness 56-167 dTex, and the outermost knitting yarn in the element-mounting portion has a fineness of 66-275 dTex, provided that the one of knitting yarns that straddle the inside sewing line of the two sewing lines as well as the outermost knitting yarn in the element-mounting portion are thicker than substantially all of the other knitting yarns.
 3. The fastener stringer according to claim 1, wherein the number of stitches where three knitting yarns are interlooping in one stitch account for at least 50% of the total number of stitches.
 4. The fastener stringer according claim 1, wherein the tape is knitted with three types of yarns in total, namely, chain knitting yarn, tricot knitting yarn and one of satin knitting yarn and modified two-needle stitch yarn.
 5. The fastener stringer according to claim 1, wherein the one of knitting yarns that straddle the inside sewing line of the two sewing lines is selected from the group consisting of tricot knitting yarn, satin knitting yarn and modified two-needle stitch yarn.
 6. The fastener stringer according to claim 1, wherein the wale which is interposed by the two needle yarns for sewing on the element row is the second wale as counted from the outermost side of the element-mounting portion.
 7. The fastener stringer according to claim 1, wherein the needle yarn has a fineness of 100-350 dTex.
 8. A slide fastener provided with the fastener stringer according to claim
 1. 9. An article on which the slide fastener according to claim 8 is sewed. 